A typical configuration for PEM fuel cells of the type that might be utilized to provide power for electric cars is illustrated in FIGS. 1 and 2. Typically, a plurality of contiguous fuel cells 7 are pressed together into a stack 8 so as to provide good electrical conductivity and no leakage of fluids, by means of tie rods 9 which draw together pressure plates 11 (sometimes referred to as “end plates”). All four sides of the fuel cell stack 8 are fitted with manifolds 12–15 for the various reactant gases, which are sealed to the stack by means of rubber sealants, gaskets and combinations thereof 18, as is described more fully with respect to FIG. 3 hereinafter. As an example, the manifold 12 may comprise an air inlet and air outlet manifold, the manifold 13 may comprise an air turnaround manifold, the manifold 14 may comprise a fuel inlet and outlet manifold, and a manifold 15 may comprise a fuel turnaround manifold. In addition, there may be a coolant inlet 20 which would feed an internal coolant manifold (not shown) and a coolant outlet 21, for coolant exiting from the internal coolant manifold. The coolant manifold may also be part of an external manifold configuration.
In the general case, vehicles must be able to be operated, parked and reoperated in ambient temperatures which fall below the freezing point of water. It is known that boot strap starts (without preheating) of fuel cell stacks from temperatures of about −20° C. cause a degradation of fuel cell performance, and many boot strap starts from freezing temperatures can render the fuel cell incapable of the performance required to operate a vehicle. In such a case, processes must be performed in order to regenerate the fuel cell and restore its performance.
To isolate a fuel cell from a freezing environment, it is obvious to consider the use of insulation. Typically, in order to prevent a fuel cell stack from reaching 0° C. in 60 hours when shut down in a −20° C. ambient, 9 centimeters of fiberglass insulation or 5 centimeters of closed foam insulation would typically be required. Use of common insulation, such as fiberglass, can more than triple the volume which the fuel cell power plant would occupy in a vehicle. When the fuel cell is to be utilized to provide electric power to a vehicle, the space taken up by the fuel cell's power plant is critical. An adequate amount of closed cell foam would approximately double the volume that a fuel cell power plant would occupy in a vehicle. It has been determined that the volumes with insulation described above are intolerable for fuel cell power plants in vehicles.